In recent years, as semiconductor technology progresses, an image sensor in an image pickup apparatus has been speeded up. Because of this, a high-speed interface has been employed in order to improve the data transmission speed from the image sensor to a signal processing unit. As such an image pickup apparatus, for example, an apparatus employing an LVDS (Low Voltage Differential Signaling) transmission scheme for data transmission from an image sensor to a signal processing unit has been proposed (for example, see Japanese Unexamined Patent Application Publication No. 2005-244709 (FIG. 1)). This LVDS transmission scheme is a scheme used to speed up the transmission speed and reduce power consumption by using differential signals of small amplitude which are opposite to each other (are different in polarity).
The above-described existing technology enables low-amplitude signals to be transmitted at high speed by using a differential amplifier.
However, there are various operation modes for such an image pickup apparatus, and there may be a case in which the transmission speed is not important such as an operation mode for picking up a low-resolution image. Even in such a case, some power is consumed in order to drive a differential amplifier. Thus, even if the frequency of the differential amplifier is lowered, it has little effect in reducing power consumption.
On the other hand, since image pickup signals supplied from the image sensor are in a certain order, if the number of active differential amplifiers, that is, the number of channels is simply changed according to an operation mode, the loss of an image pickup signal may occur.
The present invention has been made in light of such circumstances, and it is an object of the present invention to change the number of channels in accordance with an operation mode of an image pickup apparatus.